1. Field of the Invention
The present invention relates to an aerator, and particularly to an aerator for a faucet to maintain the water stream in a stable or minor variation condition upon the water pressure being varied.
2. Description of the Prior Arts
In the conventional aerators, the aerator usually has a housing and a straight cylinder being mounted in the housing. The inner surface of the housing has an annular flange for retaining the straight cylinder in place. Between the housing and the lower end of the straight cylinder, there is an annular air passage, of which the upper edge is furnished with through holes. The inside of the straight cylinder is furnished with a mixing body. After the water from the faucet flowing through the mixing body, the water will be converted into a water fall-shaped stream. The water stream and the air are to be mixed up after passing through the passage inside the straight cylinder and the notches on the edge of the straight cylinder. The lower end of the straight cylinder is furnished with vanes or a net member as a buffer to generate air bubbles in the water stream.
Generally, the straight cylinders in the prior art are not provided with any pressure control or stream volume control structure; consequently, the stream volume will be varied in proporation to the water pressure out of the faucet; it would be in-convenient to the user.
In another conventional aerator, it is designed for the purpose of saving water; the water volume of that aerator is designed and set at 2.8.+-.10% G.P.M. (U.S. standard). In the straight cylinder or the upper end of the mixing body, there is a control device for adjusting the standard water volume of the faucet. The water volume control in the aerator is designed at a standard of 80 PSIG. Whenever the water pressure is lower than 80 PSIG, the volume of water stream will be reduced immediately. Whenever the water pressure is lower than 20 PSIG, the volume of water stream would be reduced to a condition to become useless.
Still another conventional aerator has a flat upper valve element mounted on the upper end of the straight cylinder. The upper valve element has a suitable rib-shaped water passage to let the water stream flow in a scattered direction so as to have the water mixed up with the air in the mixing body to generate bubbles in the water stream. Since the upper valve element is a still part, any sands or impurities in the water might be accumulated on the top flat surface thereof; in that case, the water passage would be blocked to some extent to reduce the flow rate of water. Further, the accumulated sands or impurities might, after a long time, give rise to germs or the like to cause a sanitation problem.
A further conventional aerator has such an upper valve element on the upper end of the straight cylinder that the lower center part of the upper valve element has a post extended to the round base in the lower center part of the straight cylinder, and the lower end of the post has an annular rim; by means of the hydrodynamic pressure effect of the straight cylinder on the outside of the aerator, any sands or impurities may not be accumulated on flat surface of the upper valve element. The aforesaid prior art was disclosed in a U.S. Pat. No. 4,562,960, which is used to maintain the water clean; however, the post extended out of the faucet is usually neglected by the user without being moved manually; as a result, sands or impurities are still accumulated in the aerator of the faucet.
In the current aerator for the water faucet, the aerator developed in U.S. Pat. No. 4,562,960 is deemed the best aerator, which would cause the water stream in a faucet to have less variation; that aerator is so designed that it generates no resistance to the water stream; when it is attached to different type of faucets, the water stream would have considerable variation.